The present invention relates generally to memory management. More particularly, the present invention relates to workstations in an image handling system equipped with memory management schemes.
Presently in a hospital, medical imaging devices are preferably networked with a central image management system such as a picture archival and communications system (PACS). Medical imaging devices utilize, among others, electromagnetic radiation, x-rays, sonic waves, and photonic energy to produce images of a subject of interest, such as a patient, to aid in diagnosis and treatment of illnesses. For example, ultrasound devices are useful for viewing fetuses during prenatal care in a pregnancy. Magnetic resonance (MR) imaging systems can produce images of a wide range of tissues.
The central image management system includes a central storage unit coupled to a plurality of image workstations or terminals, such as PACS workstations. The central storage unit is configured to archive images produced by the plurality of medical imaging devices, and to retrieve images for display on one or more image workstations. Thus, the hospital can provide a plurality of medical imaging devices located through the hospital, and images produced from any of these medical imaging devices can then be retrieved and viewed by any of the plurality of image workstations.
Images are archived in the central management system in sets relating to examinations, in which each examination includes a set of images acquired at a particular time relating to a particular problem (or ailment) of a particular patient. When the physician or user on the image workstation accesses images, examinations including these images (i.e., the image data) need to be downloaded from the central storage unit to that image workstation before such images can be displayed, and thus viewed, on that image workstation. During a session on the image workstation, a plurality of examinations are typically viewed by the physician. Moreover, the physician may desire to sequentially view images from different examinations in a relatively short order (i.e., moving back and forth among different examinations).
Unfortunately, conventional image workstations are ill suited to effectively handle such examination viewing behavior or preferences. For example, a conventional image workstation only permits a few examinations to be readily accessible to the physician at any given time because the memory capacity of the workstation is such that only up to a few examinations can be stored on it. If the memory is full, the workstation may not permit any new examination to be accessed, or one or more of the downloaded or stored examinations would have to be unloaded (and thus no longer readily accessible to the physician) before any new examination can be accessed (i.e., downloaded from the central storage unit to the memory and displayed on the workstation). Thus, the physician is either limited to viewing only images from the few examinations already downloaded into the memory of the workstation, or waiting as each examination (not currently in the memory) requested by the physician is downloaded and displayed on the workstation. Otherwise the memory size requirement of the workstation would become extremely large and too costly.
Thus, there is a need for a workstation that permits a large number of examinations to be readily accessible to a user at any given time. There is a further need for a workstation that includes a memory management scheme to optimize the ready accessibility of a large number of relevant examinations to a user.